Pre-formed delivery catheters

ABSTRACT

A delivery catheter includes a pre-formed and resilient heart-wrapping segment. The segment may have a relaxed span that allows the segment to wrap around a left side of a heart from an anterior epicardial surface to a posterior epicardial surface, when the catheter is advanced along the epicardial surface, having been inserted from a sub-xiphoid access site.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 11/680,194filed Feb. 28, 2007, the disclosure of which is incorporated byreference in its entirety herein.

TECHNICAL FIELD

The present invention pertains to catheters and more particularly todelivery catheters having lumens for delivering medical devicestherethrough.

BACKGROUND

Delivery catheters are often used to position medical devices, forexample, one or more medical electrodes, at implant sites within a bodyof a patient, via minimally invasive techniques. These catheters areconstructed having a lumen, which provides a pathway to the implantsite, through which an implanting physician may pass the medical devicewithout encountering anatomical obstructions. Some delivery cathetersinclude mechanisms, such as pull-wire actuation, which allow theimplanting physician to actively change a curvature of the catheter inorder to direct a distal tip of the catheter to a target implant site;while other delivery catheters have pre-formed curvatures tailored toposition a distal tip thereof at a particular anatomical site from aparticular percutaneous access site, thus eliminating the need toactively control the curvature during the implant procedure.

In certain instances, a patient suffering from bradycardia,tachyarrhythmia and/or heart failure will benefit from electricalstimulation pacing and/or defibrillation electrodes implanted on anepicardial surface of the patient's heart. Minimally invasive methodsfor accessing the epicardial surface have been developed; these methodsmay be used by way of a mini-thoracotomy, or in conjunction with atrocar, a cannula or a needle that has been passed, via a percutaneousincision, through an interstitial space between the patient's ribs, orvia a percutaneous puncture, or stick at a sub-xiphoid location.

U.S. Pat. No. 4,991,578 describes a method for gaining access to anepicardial surface of a heart, wherein a percutaneous needle is insertedat a sub-xiphoid location until the tip of the needle pierces through apericardial sac surrounding the heart; a guide wire is then inserted,through a lumen of the needle, into the pericardial space over theepicardium, and the needle is removed. An introducer sheath or adelivery catheter may be inserted over the guide wire into thepericardial space to provide access to the epicardial surface of theheart.

Once access to the epicardial surface is established, for example, bymeans of tools provided in a pericardiocentesis kit, the implantingphysician may insert a medical device, for example, a medical electricallead, into the pericardial space. The physician will almost always needto direct the medical device within the pericardial space to a specificepicardial site where stable and effective medical therapy, according tothe patient's needs, can be delivered from the device. Thus there is aneed for delivery catheters formed to facilitate the delivery of medicaldevices to specific epicardial implant sites.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIG. 1A is a schematic anterior view of a heart within a chest, whereina pathway over an epicardial surface, from a sub-xiphoid access site, isdepicted.

FIG. 1B is a left lateral view of the heart.

FIG. 1C is a detailed section view of the access site of FIG. 1A,wherein a delivery catheter is shown inserted, according to someembodiments of the present invention.

FIG. 2 is a schematic left lateral view of some delivery catheterswrapped about the heart, according to some alternate embodiments of thepresent invention.

FIG. 3A is perspective view of a delivery catheter, according to someembodiments of the present invention.

FIGS. 3B-C are plan and end views, respectively, of the catheter shownin FIG. 3A.

FIG. 4A is perspective view of a delivery catheter, according to somealternate embodiments of the present invention.

FIGS. 4B-C are plan and end views, respectively, of the catheter shownin FIG. 4A.

FIG. 5A is perspective view of a delivery catheter, according to yetfurther embodiments of the present invention.

FIGS. 5B-C are plan and end views, respectively, of the catheter shownin FIG. 5A.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of skill in the fieldof the invention. Those skilled in the art will recognize that many ofthe examples provided have suitable alternatives that can be utilized.

FIG. 1A is a schematic anterior view of a heart 100 within a chest of apatient. FIG. 1A illustrates a percutaneous sub-xiphoid access site 10,which provides access to an epicardial surface of heart 100, and whichmay have been formed, as described above, via a percutaneous needlestick. Passage for an introducer sheath or a delivery catheter, throughsite 10, to an epicardial surface of heart 100 may be provided by aguide wire 14, having been passed through a lumen of the needle. FIG. 1Afurther illustrates indicators of locations of some chambers of theheart 100, a right atrium RA, a right ventricle RV, and a left ventricleLV, for reference, along with a general pathway, per the arrows, intoaccess site 10, for example, via guide wire 14, and along the anteriorepicardial surface and around a left lateral side of the heart to atarget site. According to embodiments of the present invention, adelivery catheter, having a pre-formed curvature and a longitudinallyextending lumen, provides for passage of a medical device, for example,a medical electrical lead, to the target site, which is located along aposterior lateral aspect of heart 100, for example, in a zone indicatedby reference number 105 in FIG. 1B, which is a left lateral view ofheart 100. Zone 105, which is in proximity to a base of the LV, has beendemonstrated to include effective left ventricular pacing sites. Thedelivery catheter may be advanced to zone 105, for example, generallyaccording to the pathway shown in FIG. 1A, preferably, within thepericardial space, beneath the pericardial sac, or over the pericardialsac, where access to within the pericardial space may be provided, forexample, via puncturing with a tool delivered through the catheter.

FIG. 2 is a schematic left lateral view of delivery catheters 300, 400and 500 hugging, or wrapped about heart 100, according to some alternateembodiments of the present invention. FIG. 2 illustrates distal portionsof all catheters 300, 400, 500 in order to compare various alternativeapproaches to zone 105 facilitated by each of catheters 300, 400, 500,having been inserted at access site 10 (FIG. 1A); each distal portion ofcatheters 300, 400, and 500 is shown terminated by a distal tip 350,450, and 550, respectively, which is disposed at a target site in zone105. (It should be noted that all of catheters 300, 400, 500 areincluded in FIG. 2 in order to illustrate various embodiments of thepresent invention side-by-side, and it is not preferred that more thanone catheter at a time be inserted to carry out methods of the presentinvention.) Each distal portion of catheters 300, 400 and 500 includes acurvature, which is pre-formed, according to manufacturing methods knownto those skilled in the art, and which facilitates the wrapping aboutheart 100 and the positioning of tips 350, 450, 550; each catheter 300,400, 500 will be described in greater detail below.

When a catheter of the present invention, for example, any of catheters300, 400, 500, is initially inserted from access site 10, for example asis illustrated in FIG. 1C, an elongate and relatively rigid element 17may be disposed within a lumen of the catheter in order to straightenthe pre-formed curvature thereof. FIG. 1C illustrates any one ofcatheters 300, 400, 500 having element 17 inserted therein to straightenthe pre-formed curvature thereof; FIG. 1C further illustrates any one ofcatheter distal tips 350, 450, 550, which extends distally from thestraightened pre-formed curvature, having a relatively tight bend formedtherein that will be described in greater detail below. According tosome methods of the present invention, wherein straightening element 17is employed, an operator, or implanting physician, may pull element 17back, proximally, or advance the catheter distally beyond the element,once the catheter has been advanced into the pericardial space, in orderto release the pre-formed curvature of the catheter while advancing thecatheter along the anterior portion of the epicardial surface and aroundthe left lateral side; the re-formed or released pre-formed curvaturecauses the catheter to wrap about the heart in a fashion similar to thatillustrated for catheters 300, 400, 500 in FIG. 2. Straightening element17 may include a longitudinally extending lumen so that element 17 maybe passed over guide wire 14 (FIG. 1A), previously inserted at site 10,or the catheter and straightening element 17, inserted therein, may bepassed through an introducer sheath 19, which has been inserted overguide wire 14. Although not necessary, such an introducer sheath mayhave a lumen sized to accommodate guide wire 14 and any of catheters300, 400, 500; some embodiments of introducer sheaths may have a duallumen construction, one lumen accommodating the guide wire and another,the catheter. According to alternate methods, introducer sheath 19serves to straighten the pre-formed curvature of the catheter, forexample, one of catheters 300, 400, 500, for initial insertion into thepericardial space; the catheter is allowed to re-assume its pre-formedshape as the catheter is advanced toward the left lateral side of theheart, beyond a distal end of introducer sheath 19, which may bedisposed anywhere within the pericardial space.

With reference to FIG. 2, it may be appreciated that, once catheters300, 400, 500 are wrapped about the heart, so that distal tips 350, 450,550 are positioned toward the posterior side of heart 100, catheters300, 400, 500 may be pushed and/or pulled, per arrow A, and/or twisted,or “torqued”, in order to adjust a position of tips 350, 450, 550 inzone 105. Those skilled in the art will further appreciate thatsidewalls of catheters 300, 400, 500 are constructed, according tomethods known to those skilled in the art, for transmission of push andtorsional forces applied to proximal ends thereof, which are disposedoutside the chest of the patient. According to preferred methods,wherein catheters are advanced from access site 10, within thepericardial space, it will be further appreciated that the pericardialsac overlying the epicardial surface of heart 100 provides a kind ofholding force over catheters 300, 400, 500, which that may furtherfacilitate the placement of catheter distal tips 350, 450, 550.

According to preferred embodiments of the present invention, tips 350,450, 550, which extend distally from the pre-formed curvatures ofcatheters 300, 400, 500, are pre-formed in a relatively tight bend, forexample, having a radius less than approximately 2 cm (0.78″),preferably approximately 1.75 cm (0.69″), such that the outer surface ofthe bend is a leading edge, when the pre-formed curvatures of catheters300, 400, 500 are straightened, for example, as described above andillustrated in FIG. 1C, for initial advancement over the epicardialsurface. The relatively tight bend can facilitate smooth forward passageof the catheter by preventing tips 350, 450, 550 from being directedoutward, toward the pericardial sac surrounding the epicardial surface,and/or from being directed inward toward the epicardial surface, ascatheters 300, 400, 500 are advanced over the epicardial surface.According to those methods, described above, which employ straighteningelement 17, straightening element 17 may be advanced within the lumen ofthe catheter only to a point proximal the relatively tight bend, whichis pre-formed in the distal tip of the preferred embodiment, so that thetight bend is not straightened by element 17, for example, as isillustrated in FIG. 1C. However, it should be noted that straighteningelement 17 may be positioned in any location along a length of thecatheter to achieve a desired stiffness and/or a desired straighteningof the catheter for initial insertion.

Sidewalls of catheters 300, 400, 500 may be formed from any suitablebiocompatible flexible and resilient material known to those skilled inthe art, an example of which is Pebax® reinforced with a stainless steelmetal braid. Although the scope of the present invention is not limitedby a particular outer diameter of catheter sidewalls, a suitable rangeof outer diameters may extend from approximately 5 F (0.065″) toapproximately 12 F (0.156″). Catheter tips 350, 450, 550 may be anintegral extension of the corresponding catheter sidewall or formed fromanother material coupled to the sidewall, for example, a relatively lowdurometer of Pebax®, silicone, or polyurethane. According to somepreferred embodiments of the present invention, a stiffness of catheters300, 400, 500 may vary along a length thereof, such that catheters 300,400, 500 have an increased flexibility in proximity to tips 350, 450,550; according to an exemplary embodiment of the present invention,stainless steel braid-reinforced sidewalls of catheters 300, 400, 500are formed with up to seven Pebax® materials having durometers rangingfrom approximately 69 D, in proximity to a proximal end of catheters300, 400, 500, to approximately 25 D at distal tips 350, 350, 550. Inorder to facilitate fluoroscopic navigation of catheters 300, 400, 500,catheter tips 350, 450, 550 may include a radiopaque marker, eithercoupled thereto, for example, a platinum band, or embedded therein, forexample, a barium sulfate powder blended into a polymer forming thetips. According to some embodiments, in order to facilitate eitherfluoroscopic or ultrasonic navigation, catheters 300, 400, 500 includeone or more radiopaque and echogenic markers formed by incorporation oftungsten carbide into at least a portion of the sidewalls thereof, forexample, as is described in commonly assigned U.S. Pat. No. 7,065,394,salient portions of which are hereby incorporated by reference. Any oftips 350, 450, 550 may include at least one electrode mounted theretoand coupled to a corresponding electrical contact at a proximal end ofcatheters 300, 400, 500, via a conductor extending within or alongsidethe sidewall thereof; the at least one electrode can, by sensing and/orstimulating, facilitate selection of an appropriate site for electricalstimulation, for example, left ventricular pacing, the stimulation siteat which any of tips 350, 450, 550 may disposed for delivery of a pacinglead thereto.

FIG. 3A is perspective view of delivery catheter 300, according to someembodiments of the present invention. FIG. 3A illustrates catheter 300including a relatively straight proximal segment 31, which extends froma proximal end 311 to a distal end 312, and a pre-formed curvature, orcurved distal segment 33, which extends from distal end 312 of proximalsegment 31. According to the illustrated embodiment, a lumen 36 extendsfrom proximal end 311 through distal tip 350 in order to provide apassageway for delivery of a medical device such as a medical electricallead. FIG. 3A further illustrates distal segment 33 including a firstcurve 331 extending in a first plane XY, and a second curve 332extending in a second plane YZ, which is approximately orthogonal tofirst plane XY and to another plane formed by X and Z axes; distal tip350 is shown extending distally from second curve 332, and, as waspreviously described for preferred embodiments, is shown formed in arelatively tight bend.

FIGS. 3B-C are plan and end views, respectively, of catheter 300. FIG.3B illustrates catheter 300 having an effective length L3 and distalsegment 33 having a span S33; and FIG. 3C illustrates second curve 332of segment 33 having a reach R332. With reference back to FIG. 2, itwill be appreciated that span S33 and reach R332 provide catheter 300with a capacity to wrap about the left lateral aspect of heart 100 fromthe anterior side, and to position tip 350 in zone 105. According to anexemplary embodiment of the present invention: effective length L3 isbetween approximately 48 cm (19″) and approximately 53 cm (21″); aformed radius of first curve 331 is between approximately 15.2 cm (6″)and approximately 16.5 cm (6.5″); span S33 is between approximately 7.6cm (3″) and approximately 8.9 cm (3.5″); and reach R332 is betweenapproximately 7.6 cm (3″) and approximately 8.1 cm (3.2″). It should benoted that the exemplary dimensions for span S33 and reach R332 arerepresentative of a relaxed state of distal segment 33 and that, sincecatheter 300 is formed from a resilient material, span S33 and reachR332 of distal segment 33 are likely to expand and/or compress, whencatheter 300 is advanced and positioned about a heart, for example,heart 100. With reference to FIG. 3C, second curve 332 may be formed asa simple or compound curve that provides for an appropriate degree ofreach R332 while conforming to a general cardiac contour from anteriorto posterior about a left lateral side, for example, as illustrated inFIG. 2; according to the exemplary embodiment described above, secondcurve 332 is compound and has a first radius r31 between approximately16.8 cm (6.6″) and approximately 17.3 cm (6.8″), and a second radius r32between approximately 4.3 cm (1.7″) and approximately 4.8 cm (1.9″).

FIG. 4A is perspective view of delivery catheter 400, according to somealternate embodiments of the present invention. FIG. 4A illustratescatheter 400 including a relatively straight proximal segment 41, whichextends from a proximal end 411 to a distal end 412, and a pre-formedcurvature, or curved distal segment 43, which extends from distal end412 of proximal segment 41. According to the illustrated embodiment, alumen 46 extends from proximal end 411 through distal tip 450 in orderto provide a passageway for delivery of a medical device such as amedical electrical lead. FIG. 4A further illustrates distal segment 43including a first curve 431 extending in a first plane XY, and a secondcurve 432 extending in a second plane 4, which is tilted away from planeYZ, per arrow T4, so that second curve 432 extends away from proximalend 411; distal tip 450 is shown extending distally from second curve432, and, as was previously described for preferred embodiments, isshown formed in a relatively tight bend.

FIGS. 4B-C are plan and end views, respectively, of catheter 400. FIG.4B illustrates catheter 400 having an effective length L4 and distalsegment 43 having a span S43; and FIG. 4C illustrates second curve 432of segment 43 having a reach R432. With reference back to FIG. 2, itwill be appreciated that span S43 and reach R432 provide catheter 400with a capacity to wrap about the left lateral aspect of heart 100 fromthe anterior side, and to position tip 450 in zone 105. According to anexemplary embodiment of the present invention: effective length L4 isbetween approximately 45 cm (17″) and approximately 48 cm (19″); aformed radius of first curve 431 is between approximately 18.3 cm (7.2″)and approximately 19.6 cm (7.7″); span S43 is between approximately 12.7cm (5″) and approximately 15.2 cm (6″); and reach R432 is betweenapproximately 9.6 cm (3.8″) and approximately 10.7 cm (4.2″). It shouldbe noted that the exemplary dimensions for span S43 and reach R432 arerepresentative of a relaxed state of distal segment 43 and that, sincecatheter 400 is formed from a resilient material, span S43 and reachR432 of distal segment 43 are likely to expand and/or compress, whencatheter 400 is advanced and positioned about a heart, for example,heart 100. With reference to FIG. 4C, second curve 432 may be formed asa simple or compound curve that provides for an appropriate degree ofreach R432, while conforming to a general cardiac contour from anteriorto posterior about a left lateral side, for example, as illustrated inFIG. 2; according to the exemplary embodiment described above, secondcurve 432 is compound and has a first radius r41 between approximately9.4 cm (3.7″) and approximately 10.4 cm (4.1″), a second radius r42between approximately 5 cm (2″) and approximately 6.1 cm (2.4″), and athird radius r43 between approximately 2.3 cm (0.9″) and approximately3.3 cm (1.3″). FIG. 4C further illustrates distal tip 450 including anoptional straight segment 440.

FIG. 5A is perspective view of delivery catheter 500, according to yetfurther embodiments of the present invention. FIG. 5A illustratescatheter 500 including a relatively straight proximal segment 51, whichextends from a proximal end 511 to a distal end 512, and a pre-formedcurvature, or curved distal segment 53, which extends from distal end512 of proximal segment 51. According to the illustrated embodiment, alumen 56 extends from proximal end 511 through distal tip 550 in orderto provide a passageway for delivery of a medical device such as amedical electrical lead. FIG. 5A further illustrates distal segment 53including a first curve 531 extending in a first plane XY, and a secondcurve 532 extending in a second plane 5, which is tilted away from planeYZ, per arrow T5, so that second curve 532 extends toward proximal end511; distal tip 550 is shown extending distally from second curve 532,and, as was previously described for preferred embodiments, is shownformed in a relatively tight bend.

FIGS. 5B-C are plan and end views, respectively, of catheter 500. FIG.5B illustrates catheter 500 having an effective length L5 and distalsegment 53 having a span S53; and FIG. 5C illustrates second curve 532of segment 53 having a reach R532. With reference back to FIG. 2, itwill be appreciated that span S53 and reach R532 provide catheter 500with a capacity to wrap about the left lateral aspect of heart 100 fromthe anterior side, and to position tip 550 in zone 105. According to anexemplary embodiment of the present invention: effective length L5 isbetween approximately 43 cm (17″) and approximately 48 cm (19″); aformed radius of first curve 531 is between approximately 5.8 cm (2.3″)and approximately 6.9 cm (2.7″); span S53 is between approximately 11.4cm (4.5″) and approximately 14 cm (5.5″); and reach R532 is betweenapproximately 4.3 cm (1.7″) and approximately 5.4 cm (2.1″). It shouldbe noted that the exemplary dimensions for span S53 and reach R532 arerepresentative of a relaxed state of distal segment 53 and that, sincecatheter 500 is formed from a resilient material, span S53 and reachR532 of distal segment 53 are likely to expand and/or compress, whencatheter 500 is advanced and positioned about a heart, for example,heart 100. With reference to FIG. 5C, second curve 532 may be formed asa simple or compound curve that provides for an appropriate degree ofreach R532, while conforming to a general cardiac contour from anteriorto posterior about a left lateral side, for example, as illustrated inFIG. 2; according to the exemplary embodiment described above, secondcurve 532 is simple, having a radius r5 between approximately 2.3 cm(0.9″) and approximately 2.8 cm (1.1″).

In the foregoing detailed description, the invention has been describedwith reference to specific embodiments. However, it may be appreciatedthat various modifications and changes can be made without departingfrom the scope of the invention as set forth in the appended claims.

1. A method for establishing a passageway for therapy delivery to anepicardial surface of a heart, the method comprising: straightening apre-formed curvature of a catheter via a straightening element, thecatheter including a longitudinally extending lumen as the passageway;advancing the straightened catheter through a pericardial sacsurrounding the heart from a sub-xiphoid access site; and advancing thecatheter distally beyond the straightening element thereby allowing thepre-formed curvature of the catheter to re-form; wherein there-formation of the pre-formed curvature causes the catheter to wraparound a left lateral side of the heart such that a distal tip of thecatheter is positioned along a posterior-lateral portion of theendocardial surface in proximity to the base.
 2. The method of claim 1,wherein the straightening element extends within the lumen of thecatheter.
 3. The method of claim 1, wherein the straightening elementextends around an exterior surface of the catheter.
 4. The method ofclaim 1, further comprising adjusting the position of the distal tip ofthe catheter along the posterior lateral portion of the heart by pushingthe catheter.
 5. The method of claim 1, further comprising adjusting theposition of the distal tip of the catheter along the posterior lateralportion of the heart by pulling the catheter.
 6. The method of claim 1,further comprising adjusting the position of the distal tip of thecatheter along the posterior lateral portion of the heart by twistingthe catheter.